Pentest Operator / Penetration Tester

System One is seeking a Pentest Operator / Penetration Tester to support and lead penetration testing engagements for High Value Asset (HVA) systems and enterprise security assessments in a Beltsville, MD onsite role. This position involves both internal and external testing, adversary emulation, and executive-ready reporting, backed by the opportunity to apply offensive security skills against mission-critical environments. Salary range: USD 120,000 - 170,000 per year.

Responsibilities

• Perform penetration testing across internal networks, external networks, web applications, enterprise systems, cloud-connected systems, and mission environments.
• Support HVA cybersecurity assessments by identifying exploitable vulnerabilities, validating security control effectiveness, and determining risk to critical systems and data.
• Execute activities including network mapping, reconnaissance, vulnerability validation, exploitation, post-exploitation analysis, and documentation of attack paths within approved Rules of Engagement.
• Draft and/or contribute to Rules of Engagement, test plans, scope documentation, and revisions to assessment procedures for management and stakeholder approval.
• Conduct external testing to determine what an outside attacker may be able to access, exploit, or exfiltrate within scope.
• Conduct internal testing focused on risk from users and systems with different access levels, including privilege escalation, lateral movement, persistence, and Active Directory attack paths.
• Support red team and adversary emulation by simulating realistic threat behavior, including targeted access objectives, command-and-control simulation, crafted test artifacts, and controlled social engineering when authorized.
• Perform web application testing against common vulnerability classes, including broken access control, authentication and authorization weaknesses, injection flaws, cross-site scripting, insecure configuration, and other OWASP Top 10 risks.
• Use offensive security tools and frameworks such as Kali Linux, Burp Suite, Metasploit, Nmap, Nessus, Wireshark, BloodHound, Impacket, Responder, Hashcat, John the Ripper, CrackMapExec, Cobalt Strike, Sliver, and similar tools within approved boundaries.
• Perform vulnerability analysis and validation using manual methods, automated tooling, and custom scripts or proof-of-concept code where appropriate.
• Support purple team and detection validation by mapping attacker behavior to defensive telemetry, identifying detection gaps, and recommending improvements to SIEM, EDR, and incident response processes.
• Analyze logs, endpoint artifacts, and network telemetry during exercises or assessments to validate whether behaviors are detected and escalated appropriately.
• Write and present evidence-based reports covering findings, affected assets, exploitability, business or mission impact, and prioritized remediation recommendations.
• Deliver technical and executive out-briefs to system owners, security operations, engineering teams, and senior leaders.
• Stay current on emerging attack techniques, offensive tooling, detection approaches, and federal cybersecurity requirements to strengthen client security posture.

Requirements

• ACTIVE and MAINTAINED TOP SECRET Federal or DoD security clearance.
• Bachelor’s degree in Cybersecurity, Information Technology, Computer Science, Information Systems, or a related field (additional relevant experience may be considered in lieu of degree).
• Minimum 5 (five) years of hands-on experience in penetration testing, red team operations, adversary emulation, vulnerability assessment, application security testing, cyber operations, or related offensive security work.
• Experience with internal and external network penetration testing, including reconnaissance, enumeration, exploitation, privilege escalation, lateral movement, and documentation of attack paths.
• Experience conducting web application penetration testing using both manual and automated techniques.
• Experience assessing Active Directory environments, Windows and Linux systems, and common enterprise network services.
• Experience with common penetration testing tools including Burp Suite, Metasploit, Nmap, Nessus, Kali Linux, Wireshark, BloodHound, Impacket, Responder, Hashcat, John the Ripper, Cobalt Strike, Sliver, or similar tools.
• Experience developing test plans, documenting Rules of Engagement, tracking assessment activities, and producing formal penetration test reports.
• Ability to explain technical findings, attack paths, business impact, and remediation options to technical and non-technical stakeholders.
• Strong written and verbal communication skills for client-ready deliverables and executive-ready summaries.
• Ability to work independently, manage multiple priorities, and collaborate across multidisciplinary teams in complex federal environments.

Technologies

• Kali Linux, Burp Suite, Metasploit, Nmap, Nessus, Wireshark, BloodHound, Impacket, Responder, Hashcat, John the Ripper, CrackMapExec, Cobalt Strike, Sliver
• OWASP Top 10, Active Directory, SIEM, EDR

What Would Be Nice To Have

• ACTIVE and MAINTAINED TOP SECRET Federal or DoD security clearance.
• Experience supporting HVA cybersecurity assessments or federal enterprise penetration testing programs.
• One or more relevant offensive security certifications such as OSCP, GPEN, GWAPT, GXPN, GRTP, PenTest+, CEH, GCIH, or similar certification.
• Experience with adversary emulation, purple team operations, detection engineering support, or validation of SIEM and EDR detection coverage.
• Experience with Cobalt Strike, Sliver, custom payload development, or command-and-control simulation in approved assessment environments.
• Experience with cloud security testing or assessment activities across AWS, Azure, or other cloud environments.
• Experience supporting incident response, threat hunting, or post-incident analysis.
• Experience creating proof-of-concept exploit examples for reports or live demonstrations in controlled, authorized environments.
• Experience mentoring junior penetration testers or leading small offensive security workstreams.
• Excellent oral and written communication and presentation skills.